The present invention relates to improved methods for the conversion of animal waste to multiple fuels and, more specifically, it relates to such conversion processes in which the associated fuels are both solid phase, multiple liquid phases and a gas phase which can be released.
Energy needs and the desire to protect the environment have resulted in efforts provide alternative sources of fuel. To date, in addition to the conventional fossil fuel sources and the use of nuclear energy, numerous alternative energy sources have been utilized such as the wind, or mechanical or thermal use of large bodies of water. Also, with respect to environmental considerations, low sulfur coal and methods for cleaning the exhaust from the use of fossil fuels have been utilized.
The U.S. Department of Energy is faced with the immense task of balancing the energy demand of our society with the environmental consequences of generating that energy. The primary focus has been on the efficiency of conversion of fuel to a useful form of energy. Energy can simply be defined as the ability to do work. The energy value of a fuel normally is measured by temperature change. Fundamentally fuels are valued by their ability to supply heat. In the traditional sense, combustion processes produce heat from the fuel. As fuel is oxidized, heat is released. The heat is converted through some mechanical means to a more useful form of energy for application. As the efficiency of the conversion increases, the negative impact on the environment decreases.
It has been suggested to convert agricultural and biological waste such as sawdust and various manures to liquid fuels and subsequently to energy (see Stiller et al., Fuel Processing Technology 49, 167, 1996 and Dadyburjor et al., Paper presented at 209.sup.th National Meeting, American Chemical Society, Anaheim, Calif., April, 1995). The initial project investigated the effects of recycling “waste” materials by using them as co-liquefaction agents for the conversion of coal to liquid fuels. See, for example, the use of shredded tires (see Sharma et al., Energy and Fuels 12, 589, 1998), plastic materials such as polyvinyl chloride, (see Zondlo, J. W., Paper presented at 214.sup.th National Meeting, American Chemical Society, Las Vegas, Nev., September, 1997) and high density polyethylene, (see Dadyburjor, D. B., Paper presented at the Tri-State Catalysis Society Spring Symposium, Charleston, W.Va., April, 1998), as well as ag- and bio-wastes.
In an effort to improve the coal liquefaction process, it was hypothesized that organics with conjugated double bonds, which are plentiful in manures and other agricultural wastes, would catalyze coal liquefaction reactions. In testing the hypothesis, it was found that the wastes did not improve the conversion of coal to liquid fuel, but the organic matter of the wastes were converted completely to fuel.
Coal is not a necessary prerequisite for fuel production from manures. Stiller et al., Co-processing of Agricultural and Biomass Waste with Coal, Fuel Processing Technology, In Press, 1996 indicates that one can produce fuel with good yields using the manure alone, along with an iron-based catalyst.
The present invention focuses on the use of waste, such as animal manure, as a source of material from which to produce liquid fuel (see, Stiller et al., Fuel Processing Technology 49, 167, 1996). The present invention improves upon previous inventions within the field, including United States Patent Application Number 20030221361, by introducing a method to reduce an ash by-product of the reaction, making the heating of the reaction more uniform, increasing the solubility of the waste, and the using of all solid and liquid by-products as a fuel.